Problem: Simplify the following expression: $z = \dfrac{6y}{8} + \dfrac{-4y}{8}$
Since the expressions have the same denominator we simply combine the numerators: $z = \dfrac{6y - 4y}{8}$ Combine like terms: $z = \dfrac{2y}{8}$ Simplify by dividing numerator and denominator by 2: $z = \dfrac{y}{4}$